Polyvinylarene polymer particles are well known in the art. An example of such particles is polystyrene. Polystyrene is prepared on a commercial scale by suspension polymerization.
EP-B-405 324 discloses such a suspension polymerization process. According to this document, styrene monomers are suspended at room temperature in an aqueous phase together with a suitable initiator and customary stabilizers and additives. Initiation of the polymerization is caused by heating the polymerization batch from room temperature to 80 to 90.degree. C. within 2 hours. Subsequently, the temperature is gradually increased to a temperature in the range of 120 to 130.degree. C.
The process disclosed in EP-B-405 324 has the disadvantage that it requires a high energy input. Namely, each new polymerization batch requires mixing of the components at room temperature and subsequent heating to 80 to 90.degree. C.
In addition, Applicant has found that the process of EP-B-405 324 results in particles with a relatively small median particle size, which makes these particles less suitable for certain applications such as insulation applications, drainage applications and sit bags.
Furthermore, Applicant has found that the process of EP-B-405 324 leads to particles having a relatively broad particle size distribution. This is undesirable, since polyvinylarene polymer particles in a particular desired size range should be formed in an adequate amount. The occurrence of oversized or undersized grains should be as small as possible, i.e. the particle size distribution should be narrow.